Pulsed and continuous-wave operation of long wavelength infrared (lambda=9.3 mu m) quantum cascade lasers

The operation of quantum cascade lasers at a wavelength (lambda similar or equal to 9.3 mu m) well within the 8-13-mu m atmospheric window is reported, A detailed study of intersubband luminescence in a vertical transition structure shows linewidths as narrow as similar to 10 meV at cryogenic temperatures, increasing to 20 meV at room temperature, Pulsed operation is demonstrated up to 220 K with a peak power approximate to 10 mW and approximate to 35 mW at 140 K, The temperature dependence of the threshold current density (J(th)) is described by a high T-0 (128 K), J(th) is also systematically studied as a function of cavity length to determine the peak gain and waveguide losses, Continuous-wave, single-mode operation is demonstrated up to 30 K with powers approximate to 2 mW.